Absence of bovine leukemia virus proviral DNA in Japanese human blood cell lines and human cancer cell lines.

Bovine leukemia virus (BLV) infects cattle worldwide and causes B-cell lymphoma in cattle. BLV has been identified in human breast and lung cancer and in blood, but the association of BLV and human cancer is controversial. In this study, we investigated the existence of BLV in 145 Japanese human blood cell lines and 54 human cancer cell lines, using a new highly sensitive PCR assay that can amplify even one copy of BLV using LTR primers different from those in previous studies on BLV provirus in breast cancer. All samples were found negative for BLV provirus, suggesting that BLV is unlikely to infect humans.